Hi all, I'm new here, but I did a short search and hadn't found any mention of a sleep timer solution for the text to speech so far. Here's a simple, though crude, way to do it. This was tested on OSX 10.5, and should work on all OX versions.

1. Bring your Mac within USB cable range of where you want to sleep while listening to your Kindle 2 text-to-speech, and make sure the Mac is plugged in to wall power.

2. Connect the Kindle 2 to the USB port on the mac. (it should mount normally as a USB drive)

6. enter in the time that you want the kindle to stop talking, i.e. the current time + how long you want the kindle to read for

7. Hit OK, and close System Preferences

8. Close the lid on your Mac laptop, or go to the Apple Menu --> Sleep. (If you have a desktop, turn your monitor off or turn it away, as it will come on full brightness when you just selected, and you don't want it to wake you up)

After a few seconds, the Kindle 2 screen will stop showing the USB symbol and return to normal use. (But don't disconnect the USB cable!)

9. Start the text-to-speech on the Kindle 2.

10. Fall asleep listening to your favorite book.

11. The Mac will wake itself up at the pre-determined time, (even if the lid is closed on a Mac laptop!) and the Kindle 2 will mount again as a USB device, thus halting the text-to-speech!

12. (The next day, after you have woken up fresh and rested) Wake the Mac back up and eject the Kindle USB drive properly. Don't just pull the USB cable out of the Mac while it's sleeping, you'll get a naughty warning from the Mac if you do.

13. Make sure you go back into Energy Saver Schedule and remove the checkbox next to 'Start or Wake up".

This is crude, but it works!

FOR DEVELOPERs:
For those of you who are Mac/Linux developers, the command-line tool to accomplish setting wake times is 'pmset' on OSX. A little Mac app that allowed you to just choose a sleep timer duration, and set the wake time for you would be much handier. I'm a hardware developer, and have contemplated making a small portable USB dongle timer which could hook up to the kindle to produce the same disk-mounting-text-to-speech-halting effect. Would anyone be interested?

Yes, but that good of speech-to-text is almost sci-fi. Dragon Naturallyspeaking will do nice TTS, but probably not a good job with a lecture, and it wouldn't work on the Kindle, yet. I would love to have a really mobile version of Dragon Naturallyspeaking available on a relatively inexpensive device such as the Kindle.